Coral stays home when the heat's on

AS the ocean gets warmer, baby coral are becoming more reluctant to leave home.

A Queensland study has found that as ocean temperatures rise more coral larvae may remain on their birth reefs rather than exploring the underwater world and finding a new system on which to settle.

This is bad news for larger reefs like the Great Barrier Reef which rely on the recruitment of larvae from other systems but good news for smaller reefs which will retain larvae that would otherwise drift elsewhere.

Study co-author James Cook University Professor Sean Connolly says this will make it more difficult for larger systems to recover after cyclones and coral bleaching because fewer larvae will disperse from other reefs.

"The loss of connectivity can make reef systems such as the Great Barrier Reef more vulnerable," Mr Connolly, from the ARC Centre of Excellence for Coral Reef Studies (Coral CoE), said.

Although smaller reefs will have better protections by retaining their larvae, they will have fewer opportunities to change their species to adapt to climate change, he says.

Study co-author Professor Andrew Baird, also from the Coral CoE, says the research shows climate change presents both challenges and opportunities to those who manage the reef.

"The stronger link between adults and recruits means an even greater benefit if we reduce local threats such as dredging and fishing," he said.

"(However) this does not reduce the need for global action on climate change."

Increased Local Retention of Reef Coral Larvae as a Result of Ocean Warming was published in the Nature Climate Change journal.